Alum treatment set for this week

Doses of alum will be applied to three areas of Canyon Lake this week, including in the Main Lake, East Bay and the area north of the causeway according to the Lake Elsinore & San Jacinto Watersheds Authority (LESJWA).

The treatment is intended to reduce algae in the lake and will be applied 7:00 a.m. to 4:00 p.m. from April 18 through April 22. The Main Lake will receive the treatment Monday through Wednesday, the East Bay on Wednesday and Thursday and the North Causeway on Thursday. Cleanup will occur on Friday.

Alum binds with phosphorus in the lake water, drops the nutrient to the lake bottom and thereby reduces algae growth in the lake, Mark Norton of the Lake Elsinore & San Jacinto Watershed Authority said.

“Canyon Lake water mostly comes from stormwater runoff from the upper watershed each year,” he said. “The runoff has high levels of nutrients that hurt water quality and threaten aquatic life.”

Alum, the method selected to provide the best results for Canyon Lake, has a proven track record of success and is safe to both humans and aquatic life, Mark said. Drinking water quality will not be affected by any of the treatment options.

Canyon Lake will remain open during the entire treatment process. Recreational users will experience little disruption during treatment application and implementation.

In order to comply with water quality regulations enforced by the state, the Lake Elsinore & Canyon Lake Nutrient Total Maximum Daily Load (TMDL) Task Force, a coalition of cities, the county and several other organizations led by LESJWA, provides funding to continue alum water treatments in Canyon Lake. The TMDL Task Force evaluated several options during the CEQA process and determined that alum application provides the best option as a step to effectively treat the entire lake in a timely manner with minimal impact to Canyon Lake residents, Mark said.

This alum application will be the 17th Canyon Lake alum application that has taken place over the years.